CO. TYRONE, Northern Ireland - A major investigation is continuing into the events of Sunday night in Cookstown, in County Tyrone, which have resulted in the deaths of three teenagers aged between 16 and seventeen.

A fourth teenager, aged 16, is in stable condition in hospital, while 2 other teenagers were treated for injuries received on the night.

"First and foremost my thoughts this morning are very much with the families of the three young people who passed away and those who were injured. It is heart-breaking that an event which should have been fun for these youngsters on St Patrick's night should end in such a terrible tragedy," PSNI Assistant Chief Constable Mark Hamilton said on Monday morning.

Events unfolded shortly before 9.30pm Sunday night when the Northern Ireland Ambulance Service received a 999 call with reports of people injured outside the hotel. They declared it a major incident and police, Fire Service and Environmental Health then also attended the scene.

Police arrived within two minutes of the call from the Ambulance Service and quickly secured the scene. They made an urgent appeal via social media to parents of the young people to come and collect them from a Friends and Family Centre which was established in the nearby Glenavon Hotel.

The investigation is at an early stage, and while the exact cause of the incident is still unknown, there were reports of a crush at the scene and initial enquiries indicate that a large group of young people were waiting to enter a disco. Police also had reports of some fighting after the incident commenced and at least one person has reported that they were assaulted.

Police on Tuesday named the three teenagers who died in the incident as 16-year-old Connor Currie from the Dungannon area, 17-year-old Lauren Bullock from the Donaghmore area and 17-year-old Morgan Barnard also from the Dungannon area.

"It is now just over 24 hours since we launched our investigation into the tragedy that unfolded at the Greenvale Hotel in Cookstown on Sunday night," Detective Chief Superintendent Raymond Murray, Head of Serious Crime Branch, said Tuesday.

"Over a day into our investigation I can tell you we have already traced the identities of over 160 witnesses and have already spoken to a number of young people who were in the queue at the Greenvale Hotel on Sunday night. Arrangements have been made to speak to many more over the coming days."

"I want to thank everyone who has spoken with us so far, however, there is still a significant number of people who were there that night, in the queue, and I need them to come forward to speak to police so we can understand what happened. Initial CCTV viewing would lead us to estimate that perhaps as many as 400 people were in the queue or car park at that time," the detective chief superintendent said.

"A number of parents have indicated they are concerned that their children, who may have been underage, were trying to enter a licensed premises. I want to reassure you, the focus of our investigation is not the age of people who were at the event – it is about trying to find answers for the families of the three teenagers who tragically died – we need to know what you saw so the heartbroken families of Connor, Lauren and Morgan know what happened to their children."

"I would urge parents to talk with your children, support them and encourage them to come forward and tell their story to police so we can get an accurate picture of events that night," Murray said.

"Talk to your children, reassure them, we know they may be scared, but again I can assure you we are only interested in establishing what happened. Their account of events on Sunday night could be crucial to establishing how Connor, Lauren and Morgan died."

"There are a number of ways you can talk to us. Detectives can be contacted at the dedicated incident room at Dungannon police station by calling 101, extension 53055. You can visit the dedicated room at the Burnavon Arts Centre in Cookstown – this is open from 10am."

Anyone with any information, images or footage can also pass it to police via this link.